1. Field of the Invention
The present invention relates generally to an optical device, and more particularly to a light module capable of changing the light into linear and parallel light and an optical lens for the light module.
2. Description of the Related Art
In present days, the touch panels and the touch systems, which provide user to operate image directly, are more and more popular in the market. Typically, there are two types of touch panels in the present market, resistive touch panels and capacitive touch panels. For a resistive touch panel, a pressure of finger touching the screen may cause a change of resistance to identify the location of the finger on the screen. However, the screen must be made of a flexible material that the surface of the screen will be worn and scratched for a time of use, and the speed of sense will slow down when one keeps pressing the same place. For a capacitive touch panel, it senses the natural current in human body when one touches the screen to identify the location of finger on the screen. However, the capacitive touch panel will not work when one wears glove or touches the screen by fingernail.
Recently, a new touch panel, photo-sensor type touch panel, is provided in the market. As shown in FIG. 1, a photo-sensor type touch panel is provided with two reflectors 110 to reflect laser rays of laser modules 120 crossing a screen 130 to be received by receivers 140. When one touches the screen 130 to block some laser rays, the specific receivers 140 will not receive the laser rays to identify the location of the finger. FIG. 2 shows another photo-sensor type touch panel, which has two micro-electromechanical systems (MEMS) to swing reflectors 210 to reflect linear laser rays of laser module 220 crossing a screen 230 to be received by receivers 240. For the same principle, when one touches the screen 240 to block some laser rays, the specific receivers 240 will not receive the laser rays to identify the location of the finger.
However, the photo-sensor type touch panel still has the following drawbacks:
1. It needs a space for the reflectors 210 and the MEMS that the photo-sensor type touch panel usually has a big size.
2. The MEMS is very expense, and it needs time to bootup that it slows down the time of sense of the photo-sensor type touch panel.
3. The use of reflectors needs the laser of great power that photo-sensor type touch panel needs more power.
In order to overcome the above drawbacks, an improved light module for the photo-sensor type touch panel, which provides a linear light without reflector, is provided. As shown in FIG. 3, Taiwan patent no. I323769 taught such light module including an optical lens 300 and a lamp 330. The optical lens 300 includes a light collector 310 and a lenticular lens array 320 with a waved surface. I323769 taught that such light module may be incorporated in street lamp or other types of lamp. However, the lamp 330 emits light to the light collector 310 and the lenticular lens array 320 in sequence to project a parallel and linear light, as shown in FIG. 4, which just meets the requirement of the photo-sensor type touch panel. However, the light module of I323769 still has some drawbacks. The light from the lamp 310 will be transformed into parallel light by the light collector 310, and all of the parallel light will be reflected by the lenticular lens array 320 at a time. Therefore, the light couldn't get a better diffusion. In addition, the lenticular lens array 320 can't provide the light with a better diffusion as well because the crests and the troughs of the waved surface will concentrate the light.
In conclusion, the conventional light modules and the optical lens still have some places to be improved.